1. Field of the Invention
This invention relates to a process for regenerating wastepaper, and more specifically to the use of deinking chemicals prepared by reaction of epoxidized derivatives of C.sub.10 -C.sub.22 carboxylic acids with an alkoxylated polyhydroxy alcohol for the regeneration of wastepaper.
Today, wastepaper is used in large quantities for the production of, for example, newsprint and hygiene paper. Brightness and color are important quality features for papers of this type. To achieve this, the printing inks have to be removed from the printed wastepaper. This is normally done by deinking processes essentially comprising two steps, namely:
1. refining the wastepaper, i.e., fiberizing in water in the presence of the chemicals required for detachment of the printing ink particles, and PA0 2. removal of the detached printing ink particles from the fiber suspension.
The second step can be carried out by washing or flotation (Ullmanns Encyclopaedie der technischen Chemie, 4th Edition. Vol. 17, pages 570-571 (1979)). In flotation, which utilizes the difference in wetability between printing inks and paper fibers, air is forced or drawn through the fiber suspension. Small air bubbles attach themselves to the printing ink particles and form a froth at the surface of the water which is removed.
The deinking of wastepaper is normally carried out at alkaline pH values in the presence of alkali metal hydroxides, alkali metal silicates, oxidative bleaches and surfactants at temperatures in the range from 30.degree. to 50.degree. C. Anionic and/or nonionic surfactants, for example soaps, ethoxylated fatty alcohols and/or ethoxylated alkyl phenols are mainly used as surfactants (Wochenblatt fuer Papierfabrikation 17, 646 to 649 (1985))
2. Discussion of Related Art
DE-OS 31 01 444 relates to a process for the deinking of wastepaper using a compound corresponding to the following general formula EQU RCOO--(CH.sub.2 CH.sub.2 O).sub.m --(AO).sub.n --R.sup.1
in which R is a C.sub.7-21 alkyl or alkenyl group, R.sup.1 is a hydrogen atom or a C.sub.1-18 alkyl, alkenyl or acyl group, AO represents C.sub.3 H.sub.6 O and C.sub.4 H.sub.8 O groups or a mixture of C.sub.2 H.sub.4 O, C.sub.3 H.sub.6 O and C.sub.4 H.sub.8 O groups, m is an integer of 1 to 100 and n is an integer of 1 to 100.
The use of ethoxylated castor oils for the deinking of printed wastepaper is known, for example, from JP 78/52705, reported in Chem. Abstr. 89, 131445j (1978), and from DE 21 48 590. The Japanese patent describes mixtures of castor oil with 10 to 400% ethylene oxide and ethoxylated nonylphenol which are suitable for the removal of printing inks from printed wastepaper. The process disclosed in DE-PS 21 48 590 is concerned with organic materials, for example paper, which are bleached with sodium chlorite in the presence of organic compounds containing at least one ethylene oxide and/or propylene oxide unit. Suitable organic compounds containing at least one alkylene oxide unit include inter alia ethoxylated castor oil.
Where ethoxylated castor oils are used, however, it has to be accepted that the quantities of castor oil and, hence, ethoxylated castor oils available on the market are subject to considerable fluctuations. Poor harvests in the main areas of cultivation, namely Brazil and India, result in shortages of the starting material, castor oil, at more or less long intervals. Accordingly, there is a need for a substitute for ethoxylated castor oils which, when used in processes for the regeneration of wastepaper, are at least comparable with the product to be replaced in regard to the deinking results obtained. Above all, the substitute product should be obtainable from a broader raw material base less vulnerable to crises and should be both ecologically and toxicologically safe.
Further, DE 39 23 393 discloses a process for regenerating wastepaper containing printing ink using an alkoxylation product of a C.sub.10 -C.sub.22 carboxylic acid or derivative thereof containing an OH group in one or more of the 9, 10, 13 and 14 positions on the carboxylic acid moiety. The alkoxylation product is obtained by epoxidizing unsaturated C.sub.10 -C.sub.22 carboxylic acids or derivatives thereof, the oxirane ring of the epoxide is then opened by reaction with hydrogen or a protic compound to form hydroxy groups, and this material is then alkoxylated to the final product.
Also, Japan 291952/88 (equivalent to European patent application number 89311550.1) is directed to a deinking composition comprising a reaction product obtained by reacting a glyceride mixture derived from neutral oil and fat with ethylene oxide and propylene oxide. The glyceride mixture contains 5 to 10%/wt of monoglycerides, 30 to 45%/wt of diglycerides, and 50 to 70%/wt of triglycerides. The reaction product has a molar ratio of ethylene oxide to propylene oxide of between 1.8 to 2.2 wherein the mole number of added ethylene oxide is between 30 and 80 per mole of glycerides.
In addition, German patent application 40 32 050.2 filed Oct. 9, 1990 relates to regenerating printed wastepaper using the reaction product of alkoxylated aliphatic alcohols, amines, carboxylic acids, and carboxylic amides with epoxidized triglycerides such as C.sub.10 -C.sub.22 carboxylic acid derivatives.